@Nedi F Hi, I have a couple of CGI Web App: these Apps, compiled with Xojo 2017r3, work fine. The same Apps (without any changes) compiled with Xojo 2018r4, don't run anymore.Error 500 Internal Server error.

Did you make sure the 2017r3 app was not running when updating your files with the 2018r4 files? If it was running when you did that, you'll definitely get an Internal Server Error 500 when attempting to run the new app.

Alternatively, did you make sure you uploaded all the newly built 2018r4 files (like the Libs and Resource files), not just the executable?

@Ralph A Did you make sure the 2017r3 app was not running when updating your files with the 2018r4 files? If it was running when you did that, you'll definitely get an Internal Server Error 500 when attempting to run the new app.

Alternatively, did you make sure you uploaded all the newly built 2018r4 files (like the Libs and Resource files), not just the executable?

These are CGI apps... I might have to re-delete the directories as try uploading again.

The main app had not been changed - it just... stopped working. So something server-side is what I suspect the issue to be.

So you tried killing the app that's not working by renaming the CGI file? And then you renamed it back again about 10 seconds later to see if it will now restart when attempting to hit it with a browser?

@Ralph A So you tried killing the app that's not working by renaming the CGI file? And then you renamed it back again about 10 seconds later to see if it will now restart when attempting to hit it with a browser?

Nah. Deleted the files and waited a minute. Then re-uploaded it. Deleted the whole directory, in fact.

Well. The CGI web app built with Xojo 2017r3 run fine. When I re-build them with Xojo 2018r4 no one of them works, and the problem is that the server doesn't find the library libunwind8 (the server error log says "error while loading shared libraries: libunwind.so.8" )The solution is to copy the libraries libunwind.so.8 and libunwind-x86_64.so.8 into the Libs folder: this way the CGI Webb Applications built with Xojo 2018r4 work fine.(Antonio Rinaldi gave me the answer).

@Nedi F Well. The CGI web app built with Xojo 2017r3 run fine. When I re-build them with Xojo 2018r4 no one of them works, and the problem is that the server doesn't find the library libunwind8 (the server error log says "error while loading shared libraries: libunwind.so.8" )The solution is to copy the libraries libunwind.so.8 and libunwind-x86_64.so.8 into the Libs folder: this way the CGI Webb Applications built with Xojo 2018r4 work fine.(Antonio Rinaldi gave me the answer).

That's a great idea. This way you can solve this problem even when you don't have access to that part of your server, as in managed server situations.

If you want to update your web app on the server, all you have. to is delete the .cgi file and within 5-10 seconds your app will stop working.For more information see this blog by @Phillip Z (all credits to Phillip for this solution)